build: transition to tsdown

[nktnet1]

Resolves #102

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (7367b7c) to head (ce31500).

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #104      +/-   ##
===========================================
+ Coverage   94.11%   100.00%   +5.88%     
===========================================
  Files           3         4       +1     
  Lines          68        65       -3     
  Branches       22        22              
===========================================
+ Hits           64        65       +1     
+ Misses          4         0       -4     

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[sonarqubecloud]

Quality Gate passed

Issues
8 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud